Pileus Capper

The wispy hoodlike appearance over this cumulus tower, known as "pileus," was evident around 6:45 PM, Tuesday, August 6, 2013. The camera was located at Bowman Meadows Drive and Archer Drive in Marion, Iowa. The tower, with echo tops around 50,000-55,000 feet, was located about 90 miles to the southwest--in NW Davis County, southwest of Ottumwa (radar image at bottom). Pileus is formed by strong updrafts at lower altitudes acting upon moist air causing the air to cool to its dew point. This storm cell was severe-warned.